A day at the museum. The main reason we came to Bilbao - to visit the Guggenheim. The museum is a magnificent piece of architecture. Its a piece of art in itself. Enough said. Spent about 3 hours looking through it. Just as amazing inside as it is outside. Worth coming to Bilbao just for that. Unfortunately, no photos of the inside - cameras aren't allowed past the entrance. But if you Google it, there will be a multitude of images of it. 
Bilbao is an amazing city . When you first arrive you find yourself thinking "Have we made a mistake coming here?". At first glance there appears to be nothing of note about the place. But the more you wander around, the more hidden gems you find. A tree lined boulevard suddenly comes into view as you round a corner, manicured gardens and fountains, a thousand year old church, paved plazas bordered by tapas bars and cafes, a cosy cafe where no one can speak English and you can't speak Spanish, but you manage to get served with what you want anyway, and the staff make it apparent they are pleased that you have chosen their establishment to eat/drink in.
Bilbao - a destination worthy of your consideration.